Structural and biochemical insights into purine-based drug molecules in hBRD2 delineate a unique binding mode opening new vistas in the design of inhibitors of the BET family

The bromodomain and extra-terminal (BET) family proteins, which are involved in chromatin function, have been shown to be promising drug targets in several pathological conditions, including cancer and inflammation. There is considerable interest in the development of BET inhibitors with novel scaffolds to modulate the epigenesis of such diseases. Here, high-resolution crystal structures of the purine class of FDA-approved drugs (theophylline, doxophylline and acyclovir) and non-FDA-approved compounds (3-methyl-7-propylxanthine and theobromine) complexed with hBRD2 bromodomains BD1 and BD2 are reported. Remarkably, a new binding site is exhibited by stacking the compounds against the WPF shelf of BD1 and BD2. This serendipitous binding, in addition to the known acetyl-lysine binding site, sufficiently anchors the ligands in the solvent-exposed region. In addition, slight variations in the lipophilicity of these molecules significantly affected the in vitro binding affinity and selectivity towards BD1 compared with BD2. This idiosyncratic binding provides a new structural framework to link these sites for the development of next-generation inhibitors of the BET family.

Selective Vulnerability to Pyrimidine Starvation in Hematologic Malignancies Revealed by AG-636, a Novel Clinical-Stage Inhibitor of Dihydroorotate Dehydrogenase

Agents targeting metabolic pathways form the backbone of standard oncology treatments, though a better understanding of differential metabolic dependencies could instruct more rationale-based therapeutic approaches. We performed a chemical biology screen that revealed a strong enrichment in sensitivity to a novel dihydroorotate dehydrogenase (DHODH) inhibitor, AG-636, in cancer cell lines of hematologic versus solid tumor origin. Differential AG-636 activity translated to the in vivo setting, with complete tumor regression observed in a lymphoma model. Dissection of the relationship between uridine availability and response to AG-636 revealed a divergent ability of lymphoma and solid tumor cell lines to survive and grow in the setting of depleted extracellular uridine and DHODH inhibition. Metabolic characterization paired with unbiased functional genomic and proteomic screens pointed to adaptive mechanisms to cope with nucleotide stress as contributing to response to AG-636. These findings support targeting of DHODH in lymphoma and other hematologic malignancies and suggest combination strategies aimed at interfering with DNA-damage response pathways.

Dihydroorotate dehydrogenase Inhibitors Target c-Myc and Arrest Melanoma, Myeloma and Lymphoma cells at S-phase

Dihydroorotate dehydrogenase (DHODH) is a rate-limiting enzyme in the de novo biosynthesis pathway of pyrimidines. Inhibition of this enzyme impedes cancer cell proliferation but the exact mechanisms of action of these inhibitors in cancer cells are poorly understood. In this study, we showed that cancer cells, namely melanoma, myeloma and lymphoma overexpressed DHODH protein and treatment with A771726 and Brequinar sodium resulted in cell cycle arrest at S-phase. Transfection with DHODH shRNA depleted DHODH protein expression and impeded the proliferation of melanoma cells. shRNA knockdown of DHODH in combination with DHODH inhibitors further reduced the cancer cell proliferation, suggesting that knockdown of DHODH had sensitized the cells to DHODH inhibitors. Cell cycle regulatory proteins, c-Myc and its transcriptional target, p21 were found down- and up-regulated, respectively, following treatment with DHODH inhibitors in melanoma, myeloma and lymphoma cells. Interestingly, knockdown of DHODH by shRNA had also similarly affected the expression of c-Myc and p21 proteins. Our findings suggest that DHODH inhibitors induce cell cycle arrest in cancer cells via additional DHODH-independent pathway that is associated with p21 up-regulation and c-Myc down-regulation. Hence, DHODH inhibitors can be explored as potential therapeutic agents in cancer therapy.

Abstract B100: ASN003, a unique B-RAF inhibitor with additional selective activity against PI3K and mTOR kinases, shows strong antitumor activity in multiple xenograft models

Various genes in RAS-RAF and PI3K pathways are frequently mutated in a wide variety of solid tumors. Concurrent double mutations are also observed quite often in a broad range of tumor types. Combined inhibition of both pathways has been shown to impart greater efficacy in multiple tumor models in animals. In order to simultaneously block these pathways, we have discovered and characterized several molecules showing dual inhibition of the RAS-RAF and PI3K pathways. ASN003 has been identified as a lead compound with potent and highly selective inhibitory activity against B-RAF, PI3K and mTOR kinases (low nM IC50). Within the PI3K family, ASN003 has high selectivity for inhibition of PI3Kα and PI3Kδ over PI3Kβ. In cell-based mechanistic studies, ASN003 did not increase phospho-ERK levels in the KRAS mutant cell line HCT116 and thus may not cause paradoxical activation of RAS/MAPK pathway in tumors. Consistent with its dual inhibition profile, ASN003 showed strong antiproliferative activity in cell lines with B-RAF and PI3K pathway mutations as well as vemurafenib (B-RAF inhibitor)-resistant cell lines. ASN003 suppressed the phosphorylation of downstream targets of B-RAF, PI3K and mTOR in pharmacodynamic studies in multiple tumor models, indicating appropriate target engagement. In in vivo efficacy studies, ASN003 showed regression in a B-RAFV600E mutant A375 xenograft model and also caused significant tumor growth inhibition in RKO and A2058 tumor models, which harbor mutations in PIK3CA or PTEN genes, respectively, in addition to the B-RAF V600E mutation. Dual targeting of the B-RAF and PI3K pathways with ASN003 has the potential to treat and/or prevent the acquired resistance to selective B-RAF inhibitors, and may also treat a broader patient population and provide greater efficacy and survival benefit than selective B-RAF inhibitors or selective PI3K pathway inhibitors alone. Due to the lack of paradoxical activation, treatment with ASN003 may not cause skin toxicities seen with pure B-RAF inhibitors. ASN003 is currently in preclinical development and is expected to enter Phase I/II clinical trials by early 2016.

Citation Format: Scott K. Thompson, Mahaboobi Jaleel, Vijay Kumar Nyavanandi, Murali Ramachandra, Hosahalli Subramanya, Aravind Basavaraju, Vaibhav Sihorkar, Roger A. Smith, Niranjan Rao, Sandeep Gupta, Sanjeeva P. Reddy. ASN003, a unique B-RAF inhibitor with additional selective activity against PI3K and mTOR kinases, shows strong antitumor activity in multiple xenograft models. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B100.

Benzimidazole derivatives as potential dual inhibitors for PARP-1 and DHODH

Poly (ADP-ribose) polymerases (PARPs) play diverse roles in various cellular processes that involve DNA repair and programmed cell death. Amongst these polymerases is PARP-1 which is the key DNA damage-sensing enzyme that acts as an initiator for the DNA repair mechanism. Dihydroorotate dehydrogenase (DHODH) is an enzyme in the pyrimidine biosynthetic pathway which is an important target for anti-hyperproliferative and anti-inflammatory drug design. Since these enzymes share a common role in the DNA replication and repair mechanisms, it may be beneficial to target both PARP-1 and DHODH in attempts to design new anti-cancer agents. Benzimidazole derivatives have shown a wide variety of pharmacological activities including PARP and DHODH inhibition. We hereby report the design, synthesis and bioactivities of a series of benzimidazole derivatives as inhibitors of both the PARP-1 and DHODH enzymes.

AFN-1252 is a potent inhibitor of enoyl-ACP reductase from Burkholderia pseudomallei--Crystal structure, mode of action, and biological activity

Melioidosis is a tropical bacterial infection caused by Burkholderia pseudomallei (B. pseudomallei; Bpm), a Gram-negative bacterium. Current therapeutic options are largely limited to trimethoprim-sulfamethoxazole and β-lactam drugs, and the treatment duration is about 4 months. Moreover, resistance has been reported to these drugs. Hence, there is a pressing need to develop new antibiotics for Melioidosis. Inhibition of enoyl-ACP reducatase (FabI), a key enzyme in the fatty acid biosynthesis pathway has shown significant promise for antibacterial drug development. FabI has been identified as the major enoyl-ACP reductase present in B. pseudomallei. In this study, we evaluated AFN-1252, a Staphylococcus aureus FabI inhibitor currently in clinical development, for its potential to bind to BpmFabI enzyme and inhibit B. pseudomallei bacterial growth. AFN-1252 stabilized BpmFabI and inhibited the enzyme activity with an IC50 of 9.6 nM. It showed good antibacterial activity against B. pseudomallei R15 strain, isolated from a melioidosis patient (MIC of 2.35 mg/L). X-ray structure of BpmFabI with AFN-1252 was determined at a resolution of 2.3 Å. Complex of BpmFabI with AFN-1252 formed a symmetrical tetrameric structure with one molecule of AFN-1252 bound to each monomeric subunit. The kinetic and thermal melting studies supported the finding that AFN-1252 can bind to BpmFabI independent of cofactor. The structural and mechanistic insights from these studies might help the rational design and development of new FabI inhibitors.

Efficacy of selective RAR-related orphan receptor gamma (RORγ) inverse agonists in psoriasis and asthma models (CCR6P.278)

Th17 cells play a key pro-inflammatory role in a variety of autoimmune diseases. The nuclear hormone receptor RORγ controls the differentiation of Th17 cells and expression of IL-17. RORγ inverse agonists were designed using a combination of approaches including structure and knowledge based methods. Compounds were screened in a RORγ radio-ligand binding assay using 3H 25-Hydroxycholesterol, as well as in a cell based reporter assay to demonstrate inverse agonism. Compounds from multiple structural classes have been identified, with IC50 in the range of 5 - 500 nM in binding assay. Co-crystal structures of RORγ in complex with known as well as in-house compounds were utilized to optimize the lead compounds. Compounds from the lead series demonstrated good activity (< 500 nM) in reporter assay. Several compounds demonstrated > 10 fold selectivity against RORα as well as other nuclear receptors. Compounds from multiple series have shown significant inhibition of IL-17 release from differentiated mouse and human Th17 cells. Lead compounds have shown good pharmacokinetic properties in mice. Efficacy of lead compounds have been demonstrated in IMQ induced Psoriasis model as well as in intranasal OVA/LPS induced asthma model. In summary, we have identified structurally diverse small molecule inverse agonists of RORγ and have demonstrated efficacy in Th17 mediated efficacy models.

Abstract B274: Discovery and characterization of a highly selective inhibitor of B-RAF, PI3K, and mTOR kinases with antitumor activity in B-RAF and B-RAF/PI3K pathway double mutant xenograft models

The RAS-RAF-MAPK and PI3K pathways are two major signaling pathways involved in the initiation and progression of a broad range of tumors. These two pathways are frequently activated in the majority of solid tumors through mutations in various components of the pathways. Inhibition of one pathway often leads to the activation of the other pathway. Preclinical studies have shown that simultaneous inhibition of these two pathways leads to greater efficacy in a broader range of tumor types. For example, despite the presence of the B-RAFV600E mutation, colorectal cancer tumors do not respond to B-RAF selective inhibitors. In contrast, the combination of B-RAF or MEK inhibitors with PI3K pathway inhibitors shows significant tumor growth inhibition in colorectal cancer xenograft models in mice. Currently, there are several clinical trials ongoing using combinations of inhibitors targeting both pathways. We employed a rational drug design approach to discover and develop a single compound with dual inhibition of both RAS-RAF-MAPK and PI3K pathways. EN3352 was identified as a lead compound with potent inhibitory activity against B-RAF, PI3K and mTOR kinases, with low nanomolar IC50 values. Profiling of EN3352 in a panel of 292 kinases showed that it is highly selective for these three kinases. Within the PI3K family, EN3352 is selective for inhibition of PI3Kα versus PI3Kβ. EN3352 showed broader anti-proliferative activity in tumor cell lines compared to the B-Raf selective inhibitors, vemurafenib and dabrafenib. EN3352 has good oral bioavailability in preclinical species and showed inhibition of phosphorylation of the downstream targets of B-RAF, PI3K and mTOR in various tumor models in mice. EN3352 showed regression in a B-RAFV600E mutant A375 xenograft model and also showed significant tumor growth inhibition in a RKO model, which harbors mutations in both B-RAF and PIK3CA genes. Dual targeting of the B-RAF and PI3K pathways with EN3352 has the potential to treat and/or prevent the acquired resistance to selective B-RAF inhibitors, and may also treat a broader patient population and provide greater efficacy and survival benefit than selective B-RAF inhibitors or selective PI3K pathway inhibitors alone.

(Disclosure: Funding for this research was provided by Endo Pharmaceuticals Inc.)

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B274.

Citation Format: Sanjeeva P. Reddy, Mahaboobi Jaleel, Vijay K. Nyavanandi, Murali Ramachandra, Hosahalli Subramanya, Aravind Basavaraju, Vaibhav Sihorkar, Roger A. Smith, Sandeep Gupta, Scott K. Thompson. Discovery and characterization of a highly selective inhibitor of B-RAF, PI3K, and mTOR kinases with antitumor activity in B-RAF and B-RAF/PI3K pathway double mutant xenograft models. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B274.

Abstract B210: Novel inhibitors of nicotinamide phosphoribosyl transferase and their evaluation in combination with bortezomib

Nicotinamide phosphoribosyl transferase (NAMPT) is the enzyme that catalyzes the rate limiting step in the salvage pathway of Nicotinamide Adenine Dinucleotide (NAD) biosynthesis. NAMPT is reported to be overexpressed in a number of cancer and inflammatory indications. Because of the requirement of NAD for a number of key biochemical pathways, inhibition of NAMPT has been shown to result in antitumor efficacy in preclinical models. NAMPT inhibitors have also been reported to enhance sensitivity to a number of targeted agents and overcome resistance to available therapies such as bortezomib resistance in multiple myeloma. In view of the sub-optimal profile of the reported first generation NAMPT inhibitors with respect to pharmacokinetics and drug-drug interaction, we sought to develop NAMPT inhibitors with the "best-in-class" profile for overcoming mechanism-based toxicities and/or resistance to current therapies. Utilizing structure-guided drug design and SAR-based approaches, we have optimized two chemical series of inhibitors of NAMPT. Determination of co-crystal structures with several de novo designed hits greatly aided in the identification of lead compounds that exhibited potent inhibition of NAMPT. Lead compounds were highly active in inhibiting proliferation that correlated well with cellular NAD depletion of cell lines derived from multiple myeloma, prostate and breast cancers. The anti-proliferative activities were rescued in NAPRT- proficient cell lines with the addition of NA due to the NAMPT independent salvage pathway for biosynthesis of NAD, confirming the mechanism of action through NAD depletion. Lead compounds exhibited desirable drug-like properties including solubility, permeability, metabolic stability, lack of CYP inhibition and pharmacokinetic exposure. In a xenograft model of pancreatic cancer, treatment with lead compounds resulted in regression of tumors with no signs of toxicity. Recent reports demonstrating the overexpression of NAMPT in bortezomib-resistant cells and a synergistic efficacy with a combination of NAMPT inhibitor and bortezomib against the resistant cells prompted us to evaluate the combination with our optimized leads. The combination of lead NAMPT inhibitors with bortezomib showed synergistic killing of cultured multiple myeloma cell lines. Evaluation of efficacy of the lead compounds as a single agent or in combination with bortezomib in xenograft models of multiple myeloma is currently underway. Modulation of NAD levels at lower doses of NAMPT inhibitors in combination with bortezomib could overcome the limitations such as mechanism-based toxicity and/or resistance of both these therapies and provide an effective treatment option for multiple myeloma.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B210.

Citation Format: Dinesh Chikkanna, Anirudha Lakshminarasimhan, Vinayak Khairnar, Sunil Panigrahi, Anuradha Ramanathan, Aparna Satyanandan, Narasimha Rao, S Karthikeyan, Kishore Narayanan, Sreevalsam Gopinath, Raghuveer Ramachandra, Hosahalli Subramanya, Chetan Pandit, Murali Ramachandra. Novel inhibitors of nicotinamide phosphoribosyl transferase and their evaluation in combination with bortezomib. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B210.

Abstract 5389: Novel inhibitors of nicotinamide phosphoribosyl transferase (NAMPT)

Nicotinamide phosphoribosyl transferase (NAMPT) is the enzyme that catalyzes the rate limiting step in the salvage pathway of Nicotinamide Adenine Dinucleotide (NAD) biosynthesis. NAMPT is reported to be overexpressed in a number of cancer and inflammatory indications. Because of the requirement of NAD as a co-factor or substrate for a number of key biochemical pathways including those catalyzed by PARP1, Sirtuins and ADP-ribosyl cyclase, inhibition of NAMPT has been shown to result in anti-tumor efficacy in preclinical models. Two NAMPT Inhibitors FK866/APO866 and GMX1778 are currently in clinical trials for oncology indications. In the presence of these clinical agents, cultured cell lines show development of resistance due to mutations underscoring the potential need for inhibitors from distinct chemical series.

Here, we report a structure-guided drug design based approach for identification of lead compounds from two chemical series selectively targeting NAMPT. Determination of co-crystal structures with several de novo designed hits greatly aided in the identification of lead compounds that exhibited potent inhibition of NAMPT against both wild type and resistance mutants (G217R and H191R) Lead compounds were highly active in inhibiting proliferation that correlated well with cellular NAD depletion in several cancer cell lines. Normal cells and selected cancer cell lines have an NAMPT independent salvage pathway for biosynthesis of NAD, which is dependent on nicotinic acid phosphoribosyltransferase (NAPRT) and Nicotinic acid (NA). The anti-proliferative activities were fully rescued in NAPRT- proficient cell lines with the addition of NA, confirming the mechanism of action through specific NAD depletion. Lead compounds from both series exhibited excellent drug-like properties including solubility, metabolic stability and permeability, and desired exposure in pharmacokinetic studies. Anti-tumor activities of these compounds including NA rescue in NAPRT-proficient tumor models are currently being evaluated in preclinical models.

Citation Format: Murali Ramachandra, Chetan Pandit, Hosahalli Subramanya, Dinesh Chikkanna, Anirudha Lakshminarasimhan, Vinayak Khairnar, Sunil Panigrahi, Anuradha Ramanathan, Aparna Satyanandan, Narasimha Rao, Arnab Bera, Kishore Narayanan, Sreevalsam Gopinath, Raghuveer Ramachandra. Novel inhibitors of nicotinamide phosphoribosyl transferase (NAMPT). [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5389. doi:10.1158/1538-7445.AM2013-5389

Value of ancillary studies in the evaluation of fine-needle aspiration specimens: Our experience

Background:

The cytological diagnosis of poorly differentiated tumors is challenging because the tumor cells may have morphologically difficult presentations in materials obtained by fine-needle aspiration cytology (FNAC). With the application of FNAC in primary diagnosis of malignant lesions, there has been a significant increase in the use of ancillary studies in the aspirated material.

Aims:

We evaluated the value of ancillary studies, namely cell blocks, immunocytochemistry (ICC) and electron microscopy (EM), in the final interpretation of FNAC smears.

Materials and Methods:

Sixty-nine cases of neoplastic swellings were subjected to FNAC. Material acquired was divided for ICC, consisting of immunoperoxidase staining of direct smears, and/or cellblocks and EM, in addition to routine light microscopy (LM). Correlation with the available histological material with immunohistochemistry and/or pertinent clinical information was used as a “gold” standard.

Results:

Five (7.2%) cases were excluded from the study, the material being necrotic or insufficient. Cell blocks were available in 46/64 (71.8%) cases, ICC evaluation was performed in 41/64 cases (64%) and EM studies were done in 57/64 cases (89%). Diagnostic accuracy of LM alone was 32/64 (50%). Cell blocks improved the diagnoses in 8/46 (17%) cases. The ICC data were diagnostic in 18/41 (43.9%) cases, helpful in 8/41 (19.6%) cases and non-helpful in 15/41 (36.5%) cases. EM studies were diagnostic in 22/57 (38.5%) cases, helpful in 18/57 (31.5%) cases and non-helpful in 17/57 (30%) cases. In 34/64 (53.1%) cases, all ancillary techniques (cell blocks, ICC and EM) were applied and their diagnostic accuracy was compared.

Conclusions:

With appropriate case selection, ancillary studies performed on aspirated material can provide useful information in FNAC.

Restorative Proctocolectomy with Ileo-anal Reservoir, a Histopathological, Histochemical, and Electron Microscopic Study

This study was conducted to investigate the nature of colonic metaplasia in ileo-anal pouches and incidence/frequency of pouchitis in the same. Biopsy specimens from 8 patients with functioning ileal pouches were studied using routine histology, mucin histochemistry and electron microscopy, over a 2 - year period. All 8 patients had villous abnormalities in the form of blunting of villi and sub total or partial villous atrophy. 6 patients had an increase in the goblet cell population and Paneth cell hyperplasia. These changes were supported by electron microscopic findings of a decrease in number and flattening of ileal type microvilli and their transformed morphologic resemblance to colonic type microvilli. All the ileal pouches also had acquired colorectal type sulphomucin, when sections stained with Alcian-blue and High Iron Diamine - Alcian blue, were studied. However, no case of pouchitis as defined in literature, was found in this study.

Cytology of hyalinising trabecular adenoma-like variant of medullary thyroid carcinoma

Medullary thyroid carcinoma is a rare thyroid neoplasm that can be either sporadic or familial. It occurs in adults, presenting as a solitary cold nodule on thyroid scan. Most are solid, firm, and non-encapsulated, and occur in the mid portion or upper half of the thyroid gland, corresponding to areas with greater numbers of C cells. We present a case of a 36-year-old female with a swelling in the front of her neck for six years. Fine needle aspiration done elsewhere revealed spindle cells, suggestive of a 'spindle cell neoplasm'. The histopathology of the thyroidectomy specimen showed features of a hyalinizing trabecular adenoma-like variant of medullary carcinoma. Subsequently, we performed aspiration on the received specimen and studied the cytological findings. The cytological diagnosis of this variant requires identification of the dual spindle and ovoid cell population and the granular neuroendocrine chromatin.

von Willebrand Disease : A Clinico-haematological Spectrum

BACKGROUND

Bleeding disorders are commonly seen in clinical practice. von Willebrand Disease (vWD), is the commonest and yet a profoundly under diagnosed cause, having a wide spectrum of clinical presentation. Of its three types, type 1 vWD (70% of the total vWD cases) has the mildest and a highly variable clinical and laboratory presentation.

METHODS

A series of ten cases of vWD were comprehensively evaluated using recommended diagnostic parameters and therapeutic interventions.

RESULTS

All major types of vWD were represented. A female preponderance, with primary presentation in the form of muco-cutaneous bleeds was observed. A positive history of consanguineous parental marriage and family history of bleeding disorder was elicited in two and three patients respectively. Nine patients were found to be anemic and thrombocytopenia was present in only one. Bleeding time by modified template (SIMPLATE) method, along with activated partial thromboplastin time (APTT) was increased in all ten cases and of these, nine had low factor VIII: C levels. Ristocetin induced platelet aggregation studies were abnormal in all the five cases it was performed. vWF:RCo activity determined in one individual was shown to be low. vWF:Ag assay was done in four cases revealing a near complete absence of von Willebrand factor antigen in one and mildly decreased levels in the other three. vWF multimer assay was advised in three cases. DDAVP, plasma derived vWF, blood products and local antifibrinolytics were used as primary modalities of treatment.

CONCLUSION

Thus, strong clinical suspicion, thorough clinical evaluation and judicious use of investigations including repeated investigations at different times are needed for making a diagnosis of vWD.

Antithrombin III assay using thrombin in disseminated intravascular coagulation (DIC), other thromboembolic disorders and hepatic diseases

Fifty cases comprising 11 cases of disseminated intravascular coagulation (DIC), 16 cases of venous thromboses and 23 cases of hepatic diseases were studied for AT III levels using clotting assay. Twelve samples were subjected to ATIII estimation by the commercially available synthetic chromogenic assay. Twenty age and sex matched controls were also analysed to find out the reference value for the techniques. Low AT III levels, if present, were correlated with other markers of DIC, viz FDP and D-dimer assays. There was a decrease in the AT III levels in all the three disease categories with a significant difference between the AT III levels of the three disease categories. In DIC, lowest levels were observed which correlated well with FDP and D-dimer levels. There was no significant difference between the average AT III levels measured by both the clotting and synthetic chromogenic assay with the former procedure being relatively inexpensive.

Subcutaneous and osteolytic rhinosporidiosis

A young man presented with multiple Subcutaneous nodules over scalp, hand, feet and osteolytic lesions of small bones of hand. Clinically and radiologically he was diagnosed as a case of Giant Cell Tumour. Aspiration cytology and biopsy proved it to be rhinosporidiosis. Epidemiological study revealed that he perhaps contracted this infection as an occupational hazard. This is the third reported case of osteolytic lesions due to rhinosporidiosis. Diagnostic dilemmas of subcutaneous and osteolytic rhinosporidiosis are discussed.